The invention relates generally to selective code reading apparatus and processes and deals more particularly with apparatus and processes for locating a code on a carrier and then reading the code.
One application among many for the invention is to locate and read a bar code on a container. The bar code may take the form of a series of substantially uniformly spaced, short and long bars arranged substantially parallel to one another on the sidewalls of the container. The code may contain a variety of information such as a mold number from which the container was formed.
A system for reading such a bar code is disclosed in U.S. patent application Ser. No. 648,229, filed Sept. 7, 1984 by Hans Martin and entitled "APPARATUS FOR READING A LINE MARKING". This patent application is assigned to the assignee of the present invention and hereby incorporated by reference as part of the present disclosure. The code reading system of the 648,229 patent application comprises a light source which illuminates the code as the container is rotated, and a linear array of optical sensors which is positioned for lengthwise illumination by reflections from each bar as the container is rotated. When any one of the sensors is activated by a reflection, measurement circuitry is activated to count the total number of sensors in the array which are simultaneously activated by the reflection. The number indicates the length of the bar or other source of reflection. Count values within a first range indicate long bars of one binary level while count values within a second range indicate short bars of the other binary level.
Sometimes however, stray marks, container imperfections or lettering occur outside the code region but within the line of sight of the optical sensors and yield readings which may be confused with the bar code.
Accordingly, a general object of the present invention is to provide a selective code reading apparatus and process which can locate a code on a carrier and distinguish it from lettering or other marks on the carrier.
A more specific object of the present invention is to provide a selective code reading apparatus and process of the foregoing type which cooperates with a bar code reader to read the code.
Another specific object of the present invention is to provide a bar code reader which can read different types of bar codes having short and long bar elements which vary in length from type to type.